Prognostic Value of Multidetector Coronary Computed Tomography Angiography in Relation to Exercise Electrocardiogram in Patients With Suspected Coronary Artery Disease

OBJECTIVES: This study was designed to determine the prognostic value of multidetector coronary computed tomography angiography (CTA) in relation to exercise electrocardiography (XECG) findings. The prognostic usefulness of coronary CTA findings of coronary artery disease in relation to XECG findings has not been explored systematically.

METHODS: Patients with suspected coronary artery disease who had undergone both coronary CTA and XECG (<90 days between tests) from 2003 through 2009 were enrolled retrospectively. Coronary CTA results were classified according to the severity of maximal stenosis (normal, mild: <40% of luminal stenosis, moderate: 40% to 69%, severe: ≥70%), XECG results were categorized as positive and negative, and Duke XECG score was calculated. Clinical follow-up data were collected for major adverse cardiac events (MACE): cardiac death, nonfatal myocardial infarction, unstable angina requiring hospitalization, and revascularization after 90 days from index coronary CTA. C-statistics were calculated to compare discriminatory values of each test.

RESULTS: Among the 2,977 (58 ± 10 years) study patients, 12% demonstrated positive XECG results. By coronary CTA, patients were categorized as normal (56%) or having mild (26%), moderate (13%), or severe (5%) disease. During a median follow-up of 3.3 years (interquartile range: 2.3 to 4.6), 97 MACE were observed and the 5-year cumulative event rate was 3.6% (95% confidence interval: 3.0 to 4.3). Although both XECG (C-statistic: 0.790) and coronary CTA (C-statistic: 0.908) improved risk stratification beyond clinical risk factors (C-statistic: 0.746, p < 0.05 for all), XECG in addition to coronary CTA (C-statistic: 0.907) did not provide better discrimination than coronary CTA alone (p = 0.389). In subgroup analyses, coronary CTA stratified risk of MACE in groups with both positive and negative XECG results (all p < 0.001 for trend). However, positive XECG results predicted risk of MACE on coronary CTA only in the moderate stenosis group (hazard ratio: 2.58, 95% confidence interval: 1.29 to 5.19, p = 0.008) and severe stenosis group (hazard ratio: 2.28, 95% confidence interval: 1.19 to 4.38, p = 0.013).

CONCLUSIONS: In patients with suspected coronary artery disease, coronary CTA discriminates future risk of MACE in patients independent of XECG results. Compared with coronary CTA, XECG has an additive prognostic value only in patients with moderate to severe stenosis on coronary CTA. 

PMID: 23103039

Posted in Computed Tomography and tagged , , , , , , .

One Comment

  1. It is interesting to see that exercise ECG has an additive prognostic value only in patients with moderate to severe CAD per CTA. However, CTA has prognostic value independent from stress test results. On the other hand this explains the stress test value in predicting risk and not necessarily in predicting the presence of obstructive CAD. One may argue that predicting risk is more important than diagnosing obstructive CAD. However, it seems that both have prognostic value and this interesting paper tries to answer why.

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